import turtle

# 数据
def circle(x0,y0, r):
    # 坐标
    pts = []
    δ = 3-2*r
    x = 0; y = int(r)
    xy= lambda x,y:[( x+x0, y+y0),( x+x0,-y+y0),
                    (-x+x0, y+y0),(-x+x0,-y+y0),
                    ( y+x0, x+y0),( y+x0,-x+y0),
                    (-y+x0, x+y0),(-y+x0,-x+y0)]
    while x<=y:
        pts += xy(x, y)
        if δ<0:
            δ += (4*x+6)
        else:
            δ += (4*(x-y)+10)
            y -= 1
        x += 1
    return pts

pts = circle(90,110, 60)

# 创建画布
turtle.setup(600,600, 300,50)
turtle.pensize(2) # 画笔大小，为1时不成像，遂为2
turtle.speed(0)
turtle.pencolor("blue")

# 画图
turtle.up()
for pt in pts:
    turtle.goto(*pt)
    turtle.down()
    turtle.goto(*pt)
    turtle.up()

# 结束
turtle.hideturtle() # 隐藏画笔箭头
turtle.done()

